Nondusting carbon pigment and process of making the same



Patented Dec. 6, 15227.

UNITE, I? S SAMUEL SHEPPARD AND LEON W. EBERLIN, OF ROCHESTER, NEW YORK, ASSIGNORS TO EASTMAN KODAK COMPANY, OF ROCHESTER, YORK, A CORPORATION OF NEW YORK.

NONDUSTING CARBON PIGMENT AND PROCESS OFJVIAKING THE SAME.

No Drawing.

This invention relates to non-dusting carbon pigments and processes of making the same. is to provide carbon pigments in such a 5 state that they do not tend to produce annoying or dangerous clouds of carbon dust and yet may be mixed especially readily into compositions without substantial loss of covering power. Another object of the invention is to provide simple and relatively inexpensive processes for producing such pigments.

Carbon pigments, such as lainpblack, gas black and other forms of carbon black, ivory black, etc., are'desirable ingredients in many compositions, because of the fact that they are fine grained, permanent and of great covering power. But in certain industries their use has lead to considerable difiiculties. If dust from these pigments mixes with the air in proper proportions, an explosive mixture is obtained which is highly dangerous. Moreover, this dust is liable to contaminate mixtures into which it is undesirable to have it enter. Furthermore, it has been diflicult 7 to incorporate such pigments into certain kinds of compositions. v

We have found that such carbon pigments, even the extremely fine-grained gas'blacks, may be brought into substantially non-dusting form by,associating with or adsorbing on each particle of carbon 21 minute amount of a waxy substance, including, for example, various'kinds of mineral, animal and vegetable Waxes, oils or higher fatty acids. lVe have also found that the simplest process for associatingthe waxy substances and the carbon particles is to mix the latter with the waxy substances while they are carried by liquids, the liquids being preferably volatile and removed to leave the waxy substances coated over eaclnof the carbon particles.

We'shall now describe several examples of our invention, but it will be understood that the latter is not limited to the details thus given, except as indicated in the" appended solids constitute a carbon pigment which is non-dusting when treated with ordinary caution.

One of the objects of this invention claim. 75 parts by weight of paraffin wax benzol is then evaporated off and the dried.

Application filed November 26, 1926. Serial No. 151,011.

In another example of our invention, 75 partsby weight of paraflin wax and 25 parts of oleic acid are dissolved in2000 parts of benzol, into which 2000 parts of the carbon pigment are mixed. The benzol is then removed, leaving the non-dusting pigment.

The evaporation of the benzol, and its recovery, say by condensation, can take place in convenient or preferred apparatus customarily used for such a recovery. Moreover, the separation of the benzol, or equivalent volatile solvent liquid can behastened by centrifuging the mixture of carbon pigment in the solution of the waxy substances. In'this way the bulk of the benzo'l is separated mechanically, and it is only necessary to evaporate off the residue of benzol in the carbon particles collected by centrifuging.

The proportions of the ingredients can vary widely without departing from our invention. For example, we may mix 2000 parts by weight of the carbon pigment in 8000 parts of benzol containing 150 parts of paraffin wax and 50 parts of either beeswax or oleic acid. This can be centrifuged as above mentioned.

"In a still further example of our invention, we may dissolve 10 parts by weight of either castor oil, or lard oil, or'cocoanut oil, or =fish oil, or Vaseline, or-mineral oil, in 400 parts by weight of benzol. Into any of the solutions thus formed, we thoroughly stir 200 parts by weight of the carbon pigment to be treated. The particles of the carbon pigment, coated with the waxy substances, may be tlen separated from the liquid. by the steps hereinabove explained.

1 Instead of using a volatile solvent of the waxy substances as the liquid vehicle for carrying them into contact with the pigment, we may even employ a non-solvent of the waxy substances. In this case the waxy substances are thoroughly emulsified in the non-solvent liquid and then the pigment is out the pigment, if desired.

ponified by the small amounts of alkali, the wise readily miscible in various kinds of cmulsification can be helped by substituting lacquers, as will be readily understood by 6 parts of soap in the above described emul those skilled inthe art of using carbon sion. The formation of the emulsion follows black in the paint and varnish industry.

well known emulsifying procedures, inten- Where the pigment is to h,- disperscd into sive agitation, jets and high-speed colloid the form of an emulsion, our product; coated mills being illustrative of the different expewith waxy substances, can be readily disdients which may be used.

scribed emulsion, allowed to stand for about ticles in our product to cling together sulfi- 30 minutes, and then centrifuged and the eiently to avoid dusting, it, nevertheless, product dried, as above described. does not bind them together in such a way In another example, 10 parts by weight of that they interfere with admixture into either oleic acid or cocoanut oil are emulsiother forms. fied in 800 parts'by weight of water c0ntain-= In. place of the waxes and fatty acids hereing 2 parts of NAOH. Into the emulsified inabove mentioned, the following may be aqueous liquid there are thoroughly stirred employed, although our invention is not in "200 parts by weight of the carbon pigment any way restricted to these illustrationsto be treated. Then the emulsion is-allowcd 'Animal oils and fats, such as neats-foot to stand, say for about one-half hour, and oil, stearin and wool grease; vegetable oils, finally filtered, o1 centrifuged to obtain the such as corn and s'oya; petroleum oils, either treated carbon. The liquid may be mildly crudeor refined, asalso petroleum greases. heated and then cooled prior to separating Having thus. described our invention. what we claim as new and desire to secure We have found that carbon pigments by Letters Patent is: treated with waxy substances, in accordance A non-dusting carbon pigment, the parwith our invention; enter into customary ticles' of which are associated with a wax compositions as readily as before our treatwhich is solid at room temperatureand rement. In some cases they enter evenmore strains the particles-from dusting and yet readily into admixture with the other inpermits'them tobe readily mixed into comgredients. F or example, where carbon black positions with compatible ingredients, the

is to be incorporated with rubber, such as size of the particles being such as to cause plantation crepe, mechanically, say in a well dusting in the absence of said wax.

known rubber mixing mill, our treatment Signed at Rochester. New York, this 19th of the pigment noticeably facilitates the day of November, 1926.

compounding operation, as well as removes the danger and trouble from excessive dust. SAMUEL E. SHEPPARD. The pigment treated by ourprocess is like- LEON W. EBERLIN.

v persed to obtain a colloidal liquid. In other The pigment is stirred into the above dewords, while our treatment causes the par- 

